48v hobby king set up options

[dogman dan]

10s in cells that charge to 4.2v is considered 36v. But it's actually just a tad low voltage. So it might seem a bit slow compared to lead or 12s lifepo4. 11s would be awkward to charge, unless you have a 12s charger.

12s should work fine with almost all 36v kits. I have heard of a few bikes or scooters with a high voltage cutoff, but most controllers do not have that.

 

[wineboyrider]

Actually, 11s lipo is closer to the same voltage as 36v lifepo4, but it's an odd series of cells some people consider. I ran 11s lipo on my electric scooter and 36v bicycle controllers without issue.

 

[friendly1uk]

Quite puzzled by the last two posts. hk lipo is 3.7v so 10 of them is 37v which is over 36.

I read a post earlier where someone set there lvc to 3.65v which meant there 10s pack would never dip to 36v (although we have found they talk nonsense)

Hot from the charger, 42v

How is 10s lipo not enough for 36v? I'm quite sure it is ideal.

Edit: The only common thread is not comparing to 36v, but rather comparing to other chemistry that is not 36v either. Which seems a pointless comparison. 36v is the target.

 

[wesnewell]

SLA charges to ~2.3V per cell, but will settle down to ~2.25V per cell within seconds of removing the charger. There nominal voltage is 2-2.1V per cell and considered 0% soc at ~1.75V per cell. In a 36v system that gives you a range of ~40.5V to 31.5V of operating voltage.
Rc lipo charged to 4.2V per cell will hold that for a long time It will be at 0% soc at ~3.3V per cell, so a 10s pack gives you a range of 42V to 33V of operating voltage.
You can do the math for other configurations. Note that you will only get about half the rated ah capacity of an sla pack at 2C discharge rate while you will get the full capacity of the rc lipo,

 

[wesnewell]

I read a post earlier where someone set there lvc to 3.65v which meant there 10s pack would never dip to 36v (although we have found they talk nonsense)

I don't know why you would think that was nonsense. I have my lvc set to 88V for my 24s pack. That's actually 3.66V per cell. 3.66V is ~ 10% soc. A figure recommended not to go below for longevity. And while many recommend to not charge above 4.1V for the same reason, I do charge mine to 4.2V as I don't think it's as critical as the lower limit where internal resistance cause the cell to heat up more. But you are right about 10S lipo being the norm for the equivalent 36V sla pack. But many go to 12s because it provides more power and more wh for a longer range and pretty much any 36V controller will support it unless it's a really crappy one.

 

[friendly1uk]

Why do you keep saying lipo is flat at 3.3v wes. Nobody agrees. You just left another thread being told the same thing, and not for the first time this year. You can never offer a shred of evidence though.

I run mine to my chosen 3v limit regularly. I'm 85% of the way through my packs rated life, and have lost 10% of the initial capacity. I think by the time I reach the 160 full cycles turnigy quote, I will still be above 80% of initial capacity. 80% being the point where they are classed as dead. Thus, My pack is performing perfectly.

What makes you think differently ?



Guided by solid facts I avoided 2.7v. So little is left below 3v that I decided to leave that for the bms to stay awake. Had I of used it, puffing would occur regularly, and movement within cheap (dirty) cells is to be avoided. So while 2.7v is the lower electrical limit, I myself impose a 3v limit for mechanical reasons. I don't nanny them at the top though. I do the full 4.2v. I use my pack extensively and now I have almost killed a pack in this configuration I feel I can offer advice, not just repeat what other people have said before. I believe you also did some testing and got different results. This is why you state 3.3v. Can you show us?


Edit: You posted as I wrote. I know you said it, but didn't want to appear to be having a go at you. I don't question that you did that, I just question your numbers in general. 3.3v being a specific figure we are all struggling with I believe. I think I'm starting to see how you did it though.

 

[wesnewell]

Why do you keep saying lipo is flat at 3.3v wes. Nobody agrees. You just left another thread being told the same thing, and not for the first time this year. You can never offer a shred of evidence though.

I keep saying it because it is true and if you ever took the time to actually test yours, you would know it. Or could could look at the test I ran some back in this thread. The photos show the state of charge. If you're not blind, you can see for yourself. The only ones that don't agree are people that have mislead. You're just a fool if you think rc lipo 0% soc is at 2.7V. Look at the test results here. I also verified the results on my Hyperion 1420i. And I don't think you'll find anyone in the thread that disagrees. Most of whom have been using rc lipo for years like me.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=47294

 

[wesnewell]

Why do you keep saying lipo is flat at 3.3v wes. Nobody agrees. You just left another thread being told the same thing, and not for the first time this year. You can never offer a shred of evidence though.

I run mine to my chosen 3v limit regularly. I'm 85% of the way through my packs rated life, and have lost 10% of the initial capacity. I think by the time I reach the 160 full cycles turnigy quote, I will still be above 80% of initial capacity. 80% being the point where they are classed as dead. Thus, My pack is performing perfectly.

What makes you think differently ?

And if you had not run your pack down to 3.0V, you would only be about 25% through your packs life and still get close to 100% of its capacity. You've got 20C lipo and are only pulling 2-5C from it. That makes a lot of difference in longevity. How old is your pack, about a year now? Mines 22 months and I still get very close to the same as when new. I don't count cycles, but I've got over 7K miles on it and expect another 7K in the next 20 months, but if it dies after 3 years I'll be happy. I've seen reports of over 900 cycles in ebike use for rc lipo. That's the difference. if you're happy with 160, then by all means, keep running them down to 3.0V

 

[friendly1uk]

Now your just getting abusive Wes. I wanted to get through this without chucking mud. I test the capacity of my pack regularly, right down to 3.0v where I have my bms disconnect the bike. I just said this, but your not listening, your just getting defensive.



Edit: Oh you have seen my testing now. Testing that proves they live up to their 160 cycle specification. Which is what I expected when I bought them. Yes I'm happy.

900 cycles is just pulling numbers from the air again isn't it. Your all talk. Like the people claiming hundreds of charge cycles, when in fact they dropped below 80% a long time ago. Your advocating the use of under 80% each time. So you never even do a full cycle, you just add up shallow cycles. Your just nannying them and telling us how you do that. How to nanny. Not how to use as intended. Thus I can document my findings with figures that tally with the manufacturer, while your talking about a pack that we know absolutely nothing about. No voltage, Ah, demand or anything else I can get a hold of. Your out there in the wilderness saying we should all follow you? I prefer my facts to be fact. They are not dead at 3.3v you just have incalculable motives.

The military charge lipo to under 4v in some situations. This obviously extends life, but then it is not the people deciding this stuff that has to carry them. It is however well researched. I could follow that, because it is fact. Not something somebody is spreading as if it is fact, with no documentation at all. You can pull any numbers between 2.7 and 4.28 and get out of specification performance. What makes 3.3v 0% soc if you don't publish the capacity you expect. It is just pie in the sky.

 

[wesnewell]

I don't pull numbers from thin air. I leave that to people with an agenda. The more than 900 cycles numbers was posted by a long time rc lipo user whose handles starts with a Y. if you want to call him a liar, do it.

 

[dogman dan]

There is a very small % of charge left, below 3.3v. The question is, how much money is it going to cost you to try to use it?

All I know is that when I have run a 72v 10 ah lico pack to 3.5v resting, the additional distance I get discharging it further is like two blocks. So 3.5v is getting very very close to the end.

I might have most of the cells at 3.3v, but one will be heading to 2.7v fast. This is not a problem if you have a bms that is monitoring individual cells. But if you don't have a bms, then you will want to be a lot more conservative about when you stop.

When you run your motor with the pack below 3.5v without a bms, you are risking driving one of those cells below 2.7v, where severe damage occurs. No pack is ever perfectly balanced. Bottom line for me is, there is NOTHING I want to try to discharge below 3.4v. Unless I want to spend $400 getting three blocks instead of two blocks further.

I don't use a bms, and I don't think Wes does either. So we will say you should stop sooner than those talking about bms protected low voltage stopping points.

 

[wineboyrider]

Simple. A 36 v ping battery is 46v hot off the charger and a 11s lipo pack is 46.2 which means the starting voltage of a 11s lipo pack is 46.2. The lvc of a lot of controllers for a 36v setup is 31v leaves a lipo at under 3.0 v. My only point with a 11s lipo on a 36v is that you can get the max voltage in under the cap limit which may or may not be 63v.

 

[friendly1uk]

I don't pull numbers from thin air. I leave that to people with an agenda. The more than 900 cycles numbers was posted by a long time rc lipo user whose handles starts with a Y. if you want to call him a liar, do it.

I was just reading a post of methods. I think he made a range of protection boards.

Lipo is meant to be run from 3.0V to 4.2V. I have thousands of cycles on RC packs where I run cells down to 2.5V and up to 4.3V over and over and over.

There is no point quoting incomplete data like this.

I have wrote too turnigy

 

[wesnewell]

WTF do I care. I've proven my point with published data. If you want to ignore it, that's totally up to you. I couldn't care less. rc lipo is at 0% soc at ~3.3V, and the data is in this thread. You might notice that the test was done on Turnigy lipo.
http://endless-sphere.com/forums/viewtopic.php?f=14&t=47294

 

[dogman dan]

Well, I still just say there is little worth trying to get below 3.3v. Damn little below 3.5v. But I have noticed that if you have a gigantic pack, that little bit left below 3.5v is more wh than it is with a 10 ah pack.

I still try to stop at about 3.65v resting, but if I need more I don't hesitate to go to deeper. But I won't go deeper than 48v resting. That's 3.4v per cell for my 14s setup. Since my pack won't have perfect balance at the bottom, that's risky enough with no bms.

I think a lot of disagreement here is being caused by comparing a bms protected lvc with a naked stopping point.

 

[friendly1uk]

You can relax Wes, they didn't reply.
I notice they sell a pack with built in lvc though, and they chose the same 3v lvc as me. http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=31315

You wouldn't be here testing this sort of thing if you didn't care. It matters.


My next build the controller takes them down to 3.2v which will likely occur under load. Then my lights will take them down to the 3v level set by the bms. It should be illuminating :|

 

[wesnewell]

That's not RC lipo either. That's the problem. You don't know wtf you're talking about. Did you even read the note at the bottom of the specs.?
Spec:
Capacity: 2200mAh
Voltage: 11.1v
Constant discharge: 1.5C (3.3amps)
Max charge rate: 1C (2.2amps)
Standard rate: 0.5c (1.1amps)
Charge cut off: 12.6v
Discharge cut off: 9.0v
Over current cut: 5 amps
Burst discharge: N/A
Weight: 139g
Size: 100x33x19mm
Plugs: JST & JST-XH

Note: This battery is only to be used in Radio Transmitters

You keep misleading people thinking you are right, when in fact you don't know crap. That's the problem I have with you. I don't care if you ruin your own stuff by running your pack into the ground. I'm just don't want others to take your ignorant data as fact and ruin their packs following your advice.

 

[recumbent]

I also run my 14s lipo without a BMS, and would never recommend running below 3.6 volts ea. The batteries clearly start to wander a bit and sag faster at lower than 3.5 voltages.

 

[dogman dan]

Without any lab data, my gut reaction is that when my batteries start sagging that much, I'm damaging them. You are surely cooking them. By then, the pack starts really heating up.

But if you lower your discharge rate enough to reduce that sag, I can see how discharging deeper could do less damage.

But, if you don't notice you passed 3.5v, and keep hammering the throttle, It's just got to be bad for the cells. Anytime you keep discharging till that pack gets all hot, it's bad. I think we can all agree on that much. Some EV's will go into a limp home mode when the pack is near the end of it's capacity, so that it does not discharge at full amps when it's that low.

 

[Ykick]

Lacking BMS and/or some form of cell level monitoring/warning deep discharging RC Lipo is best guess - black art. You really gotta know your cells and at minimum employ Cell Log, an optimistic LVC and/or those warning buzzer things to get away with it.

I’ve never, ever, regretted carrying excess battery capacity and as cells age it’s nice to not suffer the anxiety of “doom” regarding a weakening battery pack. Ample capacity also helps during cold weather conditions and it’s generally beneficial to longevity any time you consume a shallow discharge as opposed to deep discharge.

Quality BMS and installation is certainly a wonderful option and something I would do tomorrow if I knew I would be sticking with a particular cell count. However, I enjoy logging, charting and qualifying cells so I'm one of "those" and that's fine too.

 

[friendly1uk]

That's not RC lipo either. That's the problem. You don't know wtf you're talking about. Did you even read the note at the bottom of the specs.?
Spec:
Capacity: 2200mAh
Voltage: 11.1v
Constant discharge: 1.5C (3.3amps)
Max charge rate: 1C (2.2amps)
Standard rate: 0.5c (1.1amps)
Charge cut off: 12.6v
Discharge cut off: 9.0v
Over current cut: 5 amps
Burst discharge: N/A
Weight: 139g
Size: 100x33x19mm
Plugs: JST & JST-XH

Note: This battery is only to be used in Radio Transmitters

You keep misleading people thinking you are right, when in fact you don't know crap. That's the problem I have with you. I don't care if you ruin your own stuff by running your pack into the ground. I'm just don't want others to take your ignorant data as fact and ruin their packs following your advice.

As your whole post revolves around that not being RC lipo, can you explain too me why it says turnigy lipo on it, and that it's for radio transmitter. How is that not turnigy rc lipo. What is it then? lolol

How can you get things so backwards. I was just laughing at you claiming your iq is 150 in an effort to win another thread on this matter. Looking at your proof link it's a joke. Go and have a look.

Lots of people all too willing to mediate here, but non are taking your side on this, even people you pulled in. Not a soul in this whole world believes this 3.3v tripe your pedaling. Even you don't believe it now I have gone through your... work?

 

[wesnewell]

If you think that's rc lipo, you've just proven something much better than I could.

 

[stonezone]

I'm building a battery for a similar setup (oset 20") 48V 1000W motor. I just ordered 8:
https://www.hobbyking.com/hobbyking/store/__9176__Turnigy_5000mAh_6S_20C_Lipo_Pack.html
and was planning to run 4p in a series to get 12s4p at 44.4v. I haven't received the batteries yet so my options are still open. I don't necessarily need more power (although that would be nice, i'd rather get longer range than the stock batteries)

Couple of questions:
should I be running a different combo of these batteries for this motor?
I bought an eos1420i so i should be able to charge the whole thing at once but can I balance it at the same time as I charge or do i need to occasionally split it in half and balance it that way?
Finally, would this PS be adequate for my charger http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370880608964&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en

thanks!

SZ

 

[wesnewell]

Yes, you can charge it all at once with the 1420i and you don't have to split it if you run 12s4p. You do need 2 of these to parallel the 2 banks of 4 6s packs that you will have.
http://www.hobbyking.com/hobbyking/store/__32034__JST_XH_Parallel_Balance_Lead_6S_250mm_6xJST_XH_.html
No, that dc/dc converter won't work unless you hook it to another dc source, and then it will take ~36 hours to charge your pack. This is how to wire your pack. Add a fourth bank to the 3 here.